"We've spent $16 billion in this country trying to come up with a machine that can sniff better than dogs, and we haven't done it yet," said researcher Erin Perry. She is an assistant professor in the department of animal science, food and nutrition at Southern Illinois University.

"Search-and-rescue animals can save lives, protect our soldiers in the field, and locate survivors after a disaster," Perry said. "We want to know how we can manage them so we can protect their performance, because their performance impacts human lives."

Perry and her colleagues at the University of Illinois assessed stress levels and performance in search-and-rescue dogs when they were flown for 2.5 hours in the cabin of a commercial airliner, and when they were "hot loaded" into a helicopter, blades whirling, for a 30-minute flight.

Even though the dogs showed signs of stress from the travel, it did not affect their performance, the investigators found.

"They showed behavioral stress, their gut was completely turned upside down, their bloodwork showed significant effects, and it didn't matter. They still went to work and performed beautifully," said Perry, a dog handler in the U.S. Department of Homeland Security for the past 14 years.

"Even though we see physiological impacts on these dogs, they're such amazing athletes that they overcome the physical and environmental stress and just do their job," she added.

While travel stress didn't affect the dogs' work performance in these tests, stress can occasionally cause search-and-rescue dogs to miss work, the researchers noted.

Learning more about dogs' stress responses could lead to new ways to tackle it in both working and companion animals, the study authors suggested in a news release from the University of Illinois.

"We've all owned dogs that were scared of lightning, vacuum cleaners, those innocuous day-to-day experiences," Perry said. "Having a better understanding of what causes stress and how to compensate for it helps every dog, not just the ones that are out there saving lives."